4 Speed Linkage Wave Washer Kit (6) BUSHING KIT FORD TOPLOADER Mustang Fairlane.

If your toploader factory shifter vibrates it’s likely linkage play. They are joined together with wave washers, flat washers and cotter pins.

If it's ever been apart the wave washers may be gone or may just be worn out. The wave washers hold tension on the junction to prevent rattles and wear.